Per the Missouri Department of Agriculture, shipments of oyster-shell shaped insects called the Japanese maple scale (Lopholeucaspis japonica) are being transported to Missouri on nursery trees. They live underneath a protective waxy covering and can be difficult to spot because they do not stir, and they do not have legs. They attach onto tree trunks and branches and can move undetected. These pests damage trees because they pierce the trees with their mouths to suck out the tree nutrients. As a result, the insects cause an overall decline in tree and shrub health — specifically canopy thinning and twig and branch dieback.
The Japanese maple scale (JMS) was first discovered on the East Coast, but it is rapidly spreading due to the dispersion of infected plants. It feeds on other plant varieties besides the Japanese Maple, and its host range includes trees and shrubs in more than 45 genera in 27 families. It infests many of the most common nursery and landscape plants in Missouri including red maple, lilac, dogwood, redbud, pear, crabapple, cherry, magnolia, hornbeam, honey locust, stone fruits, birch and broadleaf evergreens like holly and firethorn.